Wash all produce and pat dry.
Peel, seed, and dice cucumbers.
Peel and cube watermelon.
In a blender, place cubed watermelon, diced cucumber, lemon juice, and water.
Puree until smooth.
Fill (4) 16 oz glasses with 1 cup of ice each.
Pour blended mixture over ice into each glass.
Garnish each with a slice of lemon and serve.